Energized parts guard

ABSTRACT

An energized parts guard is disclosed comprising a panel of substantially rigid, electrically insulative material wherein the substantially rigid panel further comprises a first one or more apertures and a second one or more apertures. The first one or more apertures are so dimensioned to accept one or more circuit breakers inserted into the first one or more apertures such that there is less than a 12.5 mm gap between the panel and the circuit breaker on at least two sides of the one or more circuit breakers. The second one or more apertures are positioned to facilitate access to at least one terminal of each of the one or more circuit breakers when the one or more circuit breakers are inserted into the first one or more apertures.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.15/894,296, filed Feb. 12, 2018 which is a Continuation of and claimspriority to U.S. Non-Provisional patent application Ser. No. 15/354,650filed Nov. 17, 2016, which is a Continuation of U.S. Non-Provisionalpatent application Ser. No. 14/567,832, filed Dec. 11, 2014 and entitled“Energized Parts Guard.” The foregoing patent application is herebyincorporated by reference into this application in its entirety.

FIELD

This disclosure relates to safety devices for electrical maintenance.More specifically, this disclosure relates to a device to preventcontact with exposed energized electrical conductors during electricalmaintenance.

BACKGROUND

Electrical Panel Construction

Electrical panels are used to distribute electrical energy withinbuildings. Depending on the voltage, purpose, and configuration,electrical panels may be described as “load centers,” “panelboards,”“distribution boards,” “switchboards,” “switchgear,” or by other termsused in the industry and known to those skilled in the art. For thepurposes of this disclosure, an electrical panel includes a metallicenclosure, one or more incoming power circuits (feeders or electricalpower sources), one or more outgoing power circuits (serving electricalloads), and one or more circuit-switching devices which control the flowof electricity among the circuits.

Inside the metallic enclosure of the electrical panel, the incomingcircuits may be connected to the circuit breakers directly or via anelectrical bus. Connection of the incoming circuit via an electrical busis the most common configuration and will be assumed, withoutlimitation, throughout the remainder of this application. Mostapplications will include two or three energized (“hot” or “live”) busesof different polarities and one or two neutral buses. The energizedbuses are normally of two or three different phases. Neutral buses arenormally bonded to ground potential at the building's electrical serviceentrance and allowed to electrically “float” above ground potentialthroughout the rest of the building. In demanding applications, forexample above 1000 volts, the electrical panel may also include aseparate ground bus.

The circuit-switching devices are most commonly circuit breakers.Therefore reference to “circuit breakers” throughout this applicationincludes, without limitation, other circuit-switching devices, includingswitches, fuses, and switch-fuse combinations. The circuit breakers havecontrols which are electrically insulated from the incoming and outgoingpower circuits. Each load circuit is connected to the bus through acircuit breaker. The circuit breakers allow the load circuits to bemanually de-energized using the insulated control of the circuitbreaker. The circuit breaker also automatically de-energizes the circuitin response to an overload or short circuit. Depending on theapplication, a main circuit breaker (not shown) may be provided toisolate the buses from the incoming circuits. A main circuit breakerwill often be required by code when the number of load circuits exceedsa certain number.

FIG. 1 illustrates the circuit diagram of an exemplary electrical panel.In this example, the electrical panel has two incoming circuits 100(two-phase) and twelve outgoing circuits 102. Each outgoing circuit 102is connected to a circuit breaker 104. Each circuit breaker 104 isconnected in turn to an energized bus 106. In this example, the neutralbus 108 is bonded 110 to ground. The energized buses 106, neutral bus108, and circuit breakers 104 are all contained within a groundedmetallic enclosure 114. FIG. 2 illustrates the circuit diagram for asimilar exemplary electrical panel, in this case having three incomingcircuits (three-phase).

FIG. 3 illustrates the exterior of an electrical panel 300. The metallicenclosure 114 is electrically grounded. The metallic enclosure 114normally includes a lockable door 302 and a removable front panel 304.When locked, the door 302 prevents unauthorized access to the insulatedcontrols 306 of the circuit breakers 104. When locked, cover alsoprevents removal of the front panel 304. The front panel 304 is held inplace by threaded fasteners 310.

The insulated controls 306 of the circuit breakers 104 extend through atleast one wall of the metallic enclosure 114, normally the front panel304. This allows a user to operate the circuit breaker(s) withoutexposure to any energized parts within the metallic enclosure 114.Common types of insulated controls 306 include switches, levers, andpush-buttons, although other types of controls may be used. In someconfigurations the removable front panel 304 may have permanentlyremovable sections 308 to accommodate adding circuit breakers 104 to theelectrical panel 300. These removable sections 308 are called“knockouts” because they are removed by breaking a weld or a perforationin the metallic panel, usually with a hammer, screwdriver, and pliers.If a knockout 308 is removed and no corresponding circuit breaker isadded to the electrical panel, the energized bus will be exposed in theempty breaker position. Special inserts, called “blanks,” are availablewhich snap into the front panel and prevent the energized bus from beingexposed.

The International Electrotechnical Commission (IEC) publishes standardsfor controlling access to electrical equipment. These Ingress Protection(IP) standards consist of a two-digit number. The first digit definesthe protection against the ingress of solid objects. The second digitdefines the protection against the ingress of liquids. For example, anIP31 enclosure provides protection against the ingress of solid objects2.5 mm in diameter and against water dripping from above. In the UnitedStates, the National Electrical Manufacturer's Association (NEMA)produces a similar standard for ingress protection. The IP ratings aresummarized in the table below:

TABLE 1 Solid Object Protection Object Liquid Protection size Objectsize protected protected Level against Effective against Level against 0Not No protection against 0 Not protected protected contact and ingressof objects 1 >50 mm Any large surface 1 Dripping of the body, such aswater the back of the hand, but no protection against deliberate contactwith a body part. 2 >12.5 mm Fingers or similar 2 Dripping objects.water when tilted up to 15° 3 >2.5 mm Tools, thick wires, etc. 3Spraying water 4 >1 mm Most wires, screws, etc. 4 Splashing water 5 DustIngress of dust is not 5 Water jets Protected entirely prevented, but itmust not enter in sufficient quantity to interfere with the satisfactoryoperation of the equipment; complete protection against contact. 6 DustNo ingress of dust; 6 Powerful Tight complete protection water jetsagainst contact. 7 Immersion up to 1 m 8 Immersion beyond 1 mIndustry Work Practices

When working on the circuits in the electrical panel 300, the frontpanel 304 of the metallic enclosure 114 must be removed to expose theclamped and/or bolted connections of each circuit to the bus or circuitbreakers. This work may include, but is not limited to: testing whethera circuit is energized, troubleshooting a circuit, adding a circuit,removing a circuit, upgrading a circuit, moving a circuit to a differentcircuit breaker, replacing a faulty circuit breaker, and upgrading acircuit breaker. In short, any work involving testing, moving a circuitbreaker 104, or moving a wire will likely require removing the frontpanel 304 of the metallic enclosure 114.

If any of the incoming circuits are energized, removing the front panelwill expose the worker to energized parts. Exposure to energized partscreates a hazard of electrocution and a hazard of an arc flash. An arcflash occurs when electricity “jumps” through the air from an energizedconductor to a grounded conductor or a conductor of a differentpolarity. Air is normally an insulator, so the electricity must ionizethe air, releasing light and heat. In some cases, the energy released isenough to create an explosive pressure wave and eject electricalcomponents and molten metal. While the risk of electrocution is basedprimarily on the nominal system voltage, the hazard from an arc flash isbased on both the system voltage and the short-circuit current. Unlikevoltage, available short-circuit current must be determined on apanel-by-panel basis by an engineering study, making it much moredifficult to classify the arc-flash hazard.

In the past, work safety practices focused only on reducing the risk ofelectrocution. Workers could work on energized parts if they usedappropriate Personal Protective Equipment (PPE). For example, work onenergized parts required special electrically insulated tools and/orspecially-rated electrically insulated gloves. Rules may also haverequired hard hats or boots specially rated for their electricallyinsulating properties.

Another work safety practice is called “lockout/tagout.” This practiceis intended to prevent accidents from working on an energized circuit inthe mistaken belief that the circuit is de-energized. When a circuitbreaker is opened, de-energizing the circuit, lockout/tagout requiresattaching a lock and/or tag to the insulated control of the circuitbreaker. The lock and/or tag prevents accidentally closing the circuitbreaker and energizing the circuit, which could endanger an unsuspectingperson working elsewhere on that circuit. In many circumstancesadditional devices may be temporarily fitted to the insulated control ofthe circuit breaker to accommodate the lock or tag.

As industry awareness of the arc-flash hazard grew, the OccupationalHealth and Safety Administration (OSHA), a federal agency governingworkplace safety, created new rules to reduce the risk of arc-flashinjuries. The new rules required that “[l]ive parts [above 50 volts] towhich an employee may be exposed shall be de-energized before theemployee works on or near them, unless the employer can demonstrate thatde-energizing introduces additional or increased hazards or isinfeasible due to equipment design or operational limitations.” 29 CFR1910.333(a)(1). The old practice of working on or near exposed energizedcircuits, even with appropriate PPE, is thus prohibited unless theemployer proves that de-energizing all of the circuits increases hazardsor is “infeasible”.

Energized work is allowed to avoid introducing “additional or increasedhazards” only when life-safety equipment is de-energized. For example,circuits supplying fire alarms, sprinkler pumps, and life-supportequipment may be worked-on while energized. This limitation is strictlyenforced.

Testing and troubleshooting de-energized circuits is considered“infeasible” because electrical power is needed to check an electricalcircuit's function. Therefore, testing of energized circuits is allowed,but no other work may be done on or near them. The use of “tools” (i.e.metallic tools which are likely to cause a flash-over, even if theyinsulate the user from electrocution) is specifically prohibited.

SUMMARY

An energized parts guard is disclosed to permit working in the vicinityof energized circuits without exposing an operator to the exposedenergized components. The energized parts guard is insulative. Whenproperly used, the energized parts guard prevents contact with anyexposed energized parts within an electrical panel but allows access tode-energized components to work on them

An energized parts guard is disclosed comprising a panel ofsubstantially rigid, electrically insulative material wherein thesubstantially rigid panel further comprises a first one or moreapertures and a second one or more apertures. The first one or moreapertures are so dimensioned to accept one or more circuit breakersinserted into the first one or more apertures such that there is lessthan a 12.5 mm gap between the panel and the circuit breaker on at leasttwo sides 204, 208 of the one or more circuit breakers. The second oneor more apertures are positioned to facilitate access to at least oneterminal of each of the one or more circuit breakers when the one ormore circuit breakers are inserted into the first one or more apertures.

In another embodiment, the energized parts guard includes a third one ormore apertures configured to facilitate mounting the energized partsguard to an electrical panel when the one or more circuit breakers areinserted into the first one or more apertures.

In another embodiment, the first one or more apertures of the energizedparts guard are further configured such that there is less than 12.5 mmgap between the panel and the one or more circuit breakers on at leastthree sides 202, 204, 208 of the one or more circuit breakers. Inanother embodiment, the first one or more apertures of the energizedparts guard are further configured such that there is less than 12.5 mmgap between the panel and the one or more circuit breakers on four sides202, 204, 206, 208 of the one or more circuit breakers.

In another embodiment, there is less than a 2.5 mm gap between the paneland the one or more circuit breakers on at least two sides 204, 208 ofthe one or more circuit breakers. In another embodiment there is lessthan a 2.5 mm gap between the panel and the one or more circuit breakerson at least three sides 202, 204, 208 of the one or more circuitbreakers. In another embodiment there is less than a 2.5 mm gap betweenthe panel and the one or more circuit breakers on at least four sides202, 204, 206, 208 of the one or more circuit breakers.

In another embodiment there is less than a 1 mm gap between the paneland the one or more circuit breakers on at least two sides 204, 208 ofthe one or more circuit breakers. In another embodiment there is lessthan a 1 mm gap between the panel and the one or more circuit breakerson at least three sides 202, 204, 208 of the one or more circuitbreakers. In another embodiment there is less than a 1 mm gap betweenthe panel and the one or more circuit breakers on at least four sides202, 204, 206, 208 of the one or more circuit breakers.

In another embodiment the panel of substantially rigid, electricallyinsulative material extends at least 50 mm beyond any exposed edge ofany of the one or more circuit breakers inserted into the first one ormore apertures. In another embodiment the panel of substantially rigid,electrically insulative material extends at least 50 mm from anyterminal of the one or more circuit breakers inserted into the first oneor more apertures. In another embodiment all of the edges of the panelof substantially rigid, electrically insulative material are each atleast 50 mm from any exposed conductor of the electrical panel or theone or more circuit breakers inserted into the first one or moreapertures. In another embodiment all of the edges of the panel ofsubstantially rigid, electrically insulative material are no greaterthan 50 mm from the metallic enclosure of the electrical panel.

In another embodiment, the edges of the panel of substantially rigid,electrically insulative material are configured to prevent contact withany terminals of any circuit breakers inserted into the first one ormore apertures, any electrical bus connected to any circuit breakersinserted into the first one or more apertures, and any exposedelectrical conductors connected to the circuit breakers inserted intothe first one or more apertures or the electrical bus connected to anycircuit breakers inserted into the first one or more apertures.

In another embodiment, the energized parts guard also includeselectrically insulating covers for the second one or more apertures. Inanother embodiment the insulating covers are tethered to the energizedparts guard. In another embodiment the electrically insulating coversare tethered to one another. In another embodiment the tethers betweenthe electrically insulating covers of the plurality of electricallyinsulating covers are contiguous with the electrically insulating coversthey tether.

In another embodiment the insulating covers interlock with the one ormore circuit breakers, preventing access to the circuit-breakerterminals unless the circuit breakers are in the open position.

In another embodiment the energized parts guard is so dimensioned topermit attaching a lock or tag to an insulated control of at least oneof the one or more circuit breakers when the one or more circuitbreakers are inserted into the first one or more apertures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a two-phase electrical panel illustratingthe incoming circuits, outgoing circuits, buses, and circuit breakers,in accordance with the present disclosure.

FIG. 2 is a circuit diagram of a three-phase electrical panelillustrating the incoming circuits, outgoing circuits, buses, andcircuit breakers, in accordance with the present disclosure.

FIG. 3 is an isometric drawing of the exterior of an electrical panelillustrating the metallic enclosure, the lockable front door, and theremovable front panel in accordance with the present disclosure.

FIG. 4 is a cross-section of an electrical panel with the energizedparts guard installed, illustrating the enclosure, the bus, an incomingcircuit, the circuit breakers, and the energized parts guard inaccordance with the present disclosure.

FIG. 5 is an isometric drawing of the energized parts guard illustratingits basic features in accordance with the present disclosure.

FIG. 6 is an isometric drawing of the energized parts guard with theaddition of an intervening barriers illustrating the features of both inaccordance with the present disclosure.

FIG. 7 is an isometric drawing of the energized parts guard installed inan electrical panel, without the covers on the terminal apertures,illustrating the relationship between the energized parts guard and theenclosure and circuit breakers of the electrical panel in accordancewith the present disclosure.

FIG. 8 is an isometric drawing of the energized parts guard installed inan electrical panel, with the covers on the terminal apertures and acircuit-breaker blank covering an open circuit-breaker position,illustrating the relationship between the energized parts guard and theenclosure and circuit breakers of the electrical panel in accordancewith the present disclosure.

FIG. 9A an isometric drawing of one embodiment the energized parts guardillustrating a sliding door cover obstructing the terminal aperture andinterlocking with the closed circuit breaker in accordance with thepresent disclosure.

FIG. 9B an isometric drawing of one embodiment the energized parts guardillustrating a sliding door cover exposing the terminal aperture andinterlocking with the open circuit breaker in accordance with thepresent disclosure.

FIG. 10 is a flow chart of one exemplary method of using the energizedparts guard in accordance with the present disclosure.

DETAILED DESCRIPTION

An energized parts guard is disclosed to permit working in the vicinityof energized circuits without exposing an operator to the exposedenergized components. The energized parts guard is insulative. Whenproperly used, the energized parts guard prevents contact with anyexposed energized parts within an electrical panel but allows access tode-energized components to work on them.

To facilitate an understanding of the principals and features of thedisclosed technology, illustrative embodiments are explained below. Thecomponents described hereinafter as making up various elements of thedisclosed technology are intended to be illustrative and notrestrictive. Many suitable components that would perform the same orsimilar functions as components described herein are intended to beembraced within the scope of the disclosed electronic devices andmethods. Such other components not described herein may include, but arenot limited to, for example, components developed after development ofthe disclosed technology.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise.

By “comprising” or “containing” or “including” is meant that at leastthe named compound, element, particle, or method step is present in thecomposition or article or method, but does not exclude the presence ofother compounds, materials, particles, method steps, even if the othersuch compounds, material, particles, method steps have the same functionas what is named.

It is also to be understood that the mention of one or more method stepsdoes not preclude the presence of additional method steps or interveningmethod steps between those steps expressly identified. Similarly, it isalso to be understood that the mention of one or more components in adevice or system does not preclude the presence of additional componentsor intervening components between those components expressly identified.

Referring now to FIG. 4, which illustrates a cross section of anexemplary electrical panel 300 with an energized parts guard installed,the energized electrical bus 106 is supported on insulators or aninsulative component 400 (such as a molded plastic bracket) to insulatethem from the grounded enclosure 114. The incoming circuit conductorsare typically connected 402 to the bus 106 by clamping with a threadedfastener. The method of clamping depends on the design of the panel andthe rated voltage and current of the electrical panel. For mostapplications the wires 404 of the incoming circuits 100 will be strippedof insulation 406 and the bare conductors will be inserted into a clamp414 which is tightened by turning a screw. For higher voltages and/orcurrent, a separate terminal may be crimped onto the bare conductor andthen bolted to the bus.

The load circuits are generally connected to the circuit breaker 104terminals 112 by clamping with a threaded fastener. In mostapplications, the wires of the outgoing circuits 102 will be stripped ofinsulation and the bare conductors will be inserted into a clamp whichis tightened by turning a screw. For load circuits, the clamp isnormally integral to the circuit breaker 104. For higher voltages and/orcurrent, a terminal may be crimped onto the bare conductor and thenbolted to the circuit breaker 104 or, in the case of “rack-out”breakers, a bus extension.

In many configurations the circuit breakers 104 snap into place. Inthese configurations, the circuit breakers 104 are held in place bymating features on the bus 106 and/or the insulator(s) 400 supportingthe bus 106. Circuit breakers for higher voltage and current may bebolted into place or they may be inserted or removed via a mechanism, aprocess referred to as “racking in/racking out.”

The energized parts guard 408 is made primarily of electricallyinsulating materials, such as polymers, ceramics, or wood. The energizedparts guard 408 is preferably made from a substantially-rigid,electrically-insulating polymer. The energized parts guard 408 is morepreferably made from an impact-resistant, substantially-rigid,electrically-insulating polymer. The energized parts guard 408 is mostpreferably made from a transparent, impact-resistant,substantially-rigid, electrically-insulating polymer. In one embodiment,the energized parts guard 408 may be made from polycarbonate (PC). Inanother embodiment, the parts guard may be made from a materialincluding two or more laminations of polycarbonate. In anotherembodiment, the energized parts guard 408 may be made from poly(methylmethacrylate) (PMMA). In another embodiment, the material of theenergized parts guard 408 may be treated or formulated to resistdegradation from ultraviolet light. In another embodiment, the materialof the energized parts guard 408 may be treated or formulated to resistelectrical tracking. Electrical tracking is the degradation of apolymeric insulating material over time by partial discharges ofelectricity resulting in deposition of a conductive carbon “track” onthe insulating surface.

The energized parts guard 408 includes a panel 410 with a plurality ofapertures (i.e. holes or openings) and one or more covers for theapertures. The panel 410 is a sheet of insulating material havingsufficient height and width to prevent direct exposure to any conductorsexposed by removing the front panel 304 of an electrical panel 300. Anyincidental contact with an exposed energized conductor is thus avoided.In the preferred embodiment, the height and width will match the frontpanel 304 removed from the electrical panel 300.

The panel 410 of the energized parts guard 408 is sufficiently stiff toprevent excessive flexing from incidental contact. Excessive flexing inthis case would permanently deform the panel or allow contact withexposed energized conductors. In one embodiment, sufficient stiffnessmay be achieved by a flat panel of sufficient thickness. In anotherembodiment, sufficient stiffness may be achieved by ribs, walls, orpockets which are molded into, embossed into, fastened to, or otherwiseincorporated into the panel.

Referring now to FIG. 5, which illustrates the basic features of theenergized parts guard, the energized parts guard 408 includes one ormore circuit-breaker apertures 500, which fit over the insulatedcontrols 306 of the circuit breakers 104 when the energized parts guard408 is installed on an electrical panel 300. The circuit-breakerapertures 500 are so dimensioned that when properly installed, thecircuit-breaker apertures 500 allow the insulated controls 306 toprotrude through the energized parts guard 408 while preventinginadvertent contact with the energized conductors which were exposed byremoving the front panel 304 of the electrical panel 300. The exactshape of the circuit-breaker apertures 500 depends on the exactconfiguration of the electrical panel 300, which is dependent on theelectrical panel's manufacturer and model, among other factors. In thepreferred embodiment, the circuit-breaker apertures 500 have the samedimensions as the maximum corresponding openings (i.e. with anyknockouts 308 removed) as the front panel 304 of the electrical panel300.

The energized parts guard 408 also includes a one or more terminalapertures 502. When the energized parts guard 408 is installed on anelectrical panel 300 the terminal apertures 502 are aligned withterminals 112 of the circuit breakers 104. This allows access, throughthe terminal apertures 502, to the circuit breaker terminals 112 with atool. In one embodiment, this allows accessing the circuit-breakerterminals 112 with a screwdriver to clamp or unclamp a circuitconductor.

In some embodiments the energized parts guard 408 may include a one ormore mounting apertures 504. The mounting apertures 504 are preferablypositioned and dimensioned to match the mounting arrangement of thefront panel 304 of the metallic enclosure 114. For example, if the frontpanel 304 of the metallic enclosure 114 is mounted to 4 posts within theenclosure 114 using 4 screws, the mounting apertures 504 of theenergized parts guard 408 would be four holes matching the mountingholes found in the front panel 304 of the enclosure 114.

FIG. 6 illustrates another embodiment, in which the energized partsguard 408 may include additional insulating partitions. In a firstembodiment, the additional partitions 412 are dimensioned so that anyloose or disconnected outgoing circuit conductors cannot inadvertentlytouch an exposed incoming circuit conductor. In a second embodiment,additional partitions 600 are dimensioned so that loose or disconnectedcircuit conductors cannot inadvertently touch adjacent conductors orconductive materials (e.g. adjacent outgoing circuits, the enclosure,etc.). For example, the additional partitions in the second embodimentmay separate individual incoming circuits from each other or they mayseparate individual outgoing circuits from each other. The first andsecond embodiments may be used simultaneously or independently. Infurther embodiments, additional partitions may be added when other knownfactors or situation-specific hazards warrant additional electrical orphysical guarding.

FIG. 7 illustrates the energized parts guard 408 installed on anelectrical panel 300. In some cases one or more circuit breakerpositions may be empty 702. In some embodiments, the energized partsguard 408 is dimensioned so that a lock or tag or lockout/tagout devicecan be attached to the insulated controls 306 of the one or more circuitbreakers 104.

The energized parts guard 408 may include insulated terminal covers forthe terminal apertures 502. FIG. 8 illustrates the energized parts guard408 installed on an electrical panel 300 with the insulated terminalcovers 800 and a circuit-breaker blank 804 covering an opencircuit-breaker position 702. The insulated terminal covers 800 areconfigured to completely cover each terminal aperture and to stay inplace without assistance. When properly installed, the insulatedterminal covers 800 prevent access to exposed energized parts. Theinsulated terminal covers 800 may be held in place by friction or byadditional features on the energized parts guard 408. For example, inone embodiment the insulated terminal covers 800 may be so dimensionedthat they snap into terminal apertures 502. In this embodiment, theinsulated terminal covers 800 may resemble grommets made of flexibleplastic or an elastomer. In this embodiment, the insulated terminalcovers 800 may also be tethered 802 to the energized parts guard 408and/or to each other, to prevent losing them. In another embodiment, theinsulated terminal covers 800 and the tethers 802 may be fashioned as asingle contiguous piece. For example, the insulated terminal covers 800and the tethers 802 may be molded as a single polymer component.

The preferred embodiment, which matches the opening of the removed frontpanel 304, also permits using the same circuit-breaker blanks 804 withthe energized parts guard 408 as used with the removable front panel304. Snapping the blank 804 into the energized parts guard 408 over theempty circuit breaker position 700 prevents access to the energized bus106.

In another embodiment, the insulated terminal covers 800 may be made ofrigid plastic and be configured as doors attached to the energized partsguard 408. In this embodiment, the door insulated terminal covers 900may slide back and forth or may swing on a hinge.

In a further embodiment, illustrated in FIGS. 9A and 9B, the doorinsulated terminal covers 900 may interlock with the insulated controls306 of the circuit breakers 104. The interlock prevents opening of thedoor cover unless the insulated control of the circuit breaker 104 is inthe open position. For example, a sliding door cover may include anadditional slot 902 which fits over the control lever of the circuitbreaker, preventing the door cover from sliding open when the circuitbreaker 104 is closed because it physically interferes with the lever ofthe circuit breaker. A similar interlock may be used on hinged doorinsulated terminal covers.

FIG. 10 illustrates an exemplary method for using the energized partsguard to remove an outgoing circuit from an electrical panel. At 1000,the door is unlocked and opened. At 1002 the front panel is removed. At1004, any diagnostic testing or troubleshooting is performed on theexposed energized conductors, if needed. At 1006, the energized partsguard is installed over the circuit breaker controls. At 1008, thecircuit breaker for the outgoing circuit to be removed is opened,de-energizing the circuit. At 1010, a lock and/or tag is applied to theopened circuit breaker, if required by safety rules. At 1012, theinsulating cover over the terminal of the opened circuit breaker isremoved, exposing the terminal aperture. At 1014, the exposed terminalis tested to confirm the circuit it de-energized. If not, additionaltroubleshooting may be required. At 1016, an appropriate tool, such as ascrewdriver, is inserted through the terminal aperture. At 1018, thewire for the outgoing circuit is disconnected from the circuit breakerusing the tool. At 1020, the wire is removed from the circuit breaker.If appropriate, the wire may be pulled back though conduit to itsorigin, or it may be temporarily capped with a wire nut, or it may beconnected to the neutral bus for safety. At 1022, the energized partsguard is removed. At 1024, the front panel is replaced. At 1026, thedoor is closed and locked.

The design and functionality described in this application is intendedto be exemplary in nature and is not intended to limit the instantdisclosure in any way. Those having ordinary skill in the art willappreciate that the teachings of the disclosure may be implemented in avariety of suitable forms, including those forms disclosed herein andadditional forms known to those having ordinary skill in the art.

While certain embodiments of this disclosure have been described inconnection with what is presently considered to be the most practicaland various embodiments, it is to be understood that this disclosure isnot to be limited to the disclosed embodiments, but on the contrary, isintended to cover various modifications and equivalent arrangementsincluded within the scope of the appended claims. Although specificterms are employed herein, they are used in a generic and descriptivesense only and not for purposes of limitation.

This written description uses examples to disclose certain embodimentsof the technology and also to enable any person skilled in the art topractice certain embodiments of this technology, including making andusing any apparatuses or systems and performing any incorporatedmethods. The patentable scope of certain embodiments of the technologyis defined in the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

The invention claimed is:
 1. A power circuit-breaker enclosurecomprising: a housing; one or more circuit breakers electricallyconnected to an electrical bus; an insulating guard, said insulatingguard comprising a sheet of substantially rigid, electrically insulativematerial wherein the substantially rigid sheet further comprises a firstone or more apertures and a second one or more apertures; wherein theone or more circuit breakers are positioned in the first one or moreapertures and the first one or more apertures are further dimensioned toprevent accidental contact with any exposed electrical part within theenclosure on at least two sides of the one or more circuit breakers; andwherein the second one or more apertures are positioned to facilitateaccess to at least one terminal of the one or more circuit breakers andto prevent accidental contact with any exposed electrical part withinthe enclosure.
 2. The power circuit-breaker enclosure of claim 1 whereinthe first one or more apertures are further dimensioned to preventaccidental contact with any exposed electrical part within the enclosureon at least three sides of the one or more circuit breakers.
 3. Thepower circuit-breaker enclosure of claim 2 wherein the first one or moreapertures are further dimensioned to prevent accidental contact with anyexposed electrical part within the enclosure on at least four sides ofthe one or more circuit breakers.
 4. The power circuit-breaker enclosureof claim 1 wherein the sheet of substantially rigid, electricallyinsulative material extends beyond any exposed edge of any of the one ormore circuit breakers to prevent accidental contact with any exposedelectrical part within the enclosure.
 5. The power circuit-breakerenclosure of claim 1 wherein the sheet of substantially rigid,electrically insulative material further comprises a plurality of edgesdimensioned to prevent a hand from reaching into the enclosure betweenthe edges of the sheet of substantially rigid, electrically insulativematerial and the housing.
 6. The power circuit-breaker enclosure ofclaim 1 wherein the sheet of substantially rigid, electricallyinsulative material further comprises a plurality of edges which areconfigured to prevent contact with: any terminals of any of the one ormore circuit breakers, except through the second one or more apertures;the electrical bus connected to any of the one or more circuit breakers;or any exposed electrical conductors connected to the one or morecircuit breakers or connected to the electrical bus connected to any ofthe one or more circuit breakers.
 7. The power circuit-breaker enclosureof claim 1 further comprising one or more electrically insulating coversfor the second one or more apertures.
 8. The power circuit-breakerenclosure of claim 7 wherein the one or more insulating covers aretethered to the insulating guard.
 9. The power circuit-breaker enclosureof claim 7 wherein the one or more electrically insulating coverscomprise a plurality of electrically insulating covers which aretethered to one another by one or more tethers.
 10. The powercircuit-breaker enclosure of claim 7 wherein one or more the insulatingcovers each interlock with one of the one or more circuit breakers,preventing access to the terminals of the one or more interlockedcircuit breakers unless the one or more interlocked circuit breakers arein the open position.
 11. The power circuit-breaker enclosure of claim 1further comprising an insulative barrier positioned on the back side ofthe substantially rigid sheet.
 12. The power circuit-breaker enclosureof claim 11 wherein the insulating barrier is configured to separate afirst circuit breaker of the one or more circuit breakers from a secondcircuit breaker of the one or more circuit breakers.
 13. The powercircuit-breaker enclosure of claim 12 wherein the insulating barrier isfurther configured to separate a line-side terminal of the first circuitbreaker of the one or more circuit breakers from a line-side terminal ofthe second circuit breaker of the one or more circuit breakers.
 14. Thepower circuit-breaker enclosure of claim 11 wherein the insulatingbarrier is positioned between two of the second one or more apertures.15. The power circuit-breaker enclosure of claim 11 wherein theinsulating barrier is positioned between the first one or more aperturesand a top edge of the substantially rigid sheet.
 16. The powercircuit-breaker enclosure of claim 1 further comprising a plurality ofbarriers positioned on the back side of the substantially rigid sheet,the plurality of barriers positioned on the back side of thesubstantially rigid sheet comprising: a barrier positioned between thefirst one or more apertures and a top edge of the substantially rigidsheet; and one or more barriers positioned to separate individualapertures of the second one or more apertures from each other.
 17. Thepower circuit-breaker enclosure of claim 1 further comprising aplurality of barriers positioned on the back side of the substantiallyrigid sheet, the plurality of barriers positioned on the back side ofthe substantially rigid sheet comprising: a barrier positioned betweenthe first one or more apertures and a top edge of the substantiallyrigid sheet; and one or more barriers positioned to separate a pluralityof line-side terminals of the one or more circuit breakers from eachother.
 18. The power circuit-breaker enclosure of claim 1 furthercomprising an insulating blank dimensioned to cover a portion of thefirst one or more apertures of the insulating guard to preventaccidental contact with any exposed electrical part within theenclosure.
 19. The power circuit-breaker enclosure of claim 18 whereinthe blank is further dimensioned to snap into one of the first one ormore apertures of the insulating guard.
 20. The power circuit-breakerenclosure of claim 19 wherein the blank is further dimensioned to have awidth equal to an integer multiple of one of the one or more circuitbreakers.
 21. A method of preventing unintended shock or exposure toelectrical discharge comprising: installing an insulating guard in anelectrical panel to prevent contacting exposed energized electricalelements in the electrical panel during electrical maintenance of theelectrical panel, wherein the insulating guard is electrically isolatingand includes one or more openings dimensioned to prevent accidentalcontact with the exposed energized electrical elements in the electricalpanel, removing a front panel of the electrical panel; and installingthe insulating guard in place of the front panel, so that one or morecircuit breakers of the electrical panel are received in the one or moreopenings of the insulating guard.
 22. The method of claim 21, furthercomprising: ensuring that one of the one or more circuit breakers of theelectrical panel is in an electrically open state; inserting a tool intoone of the openings positioned to facilitate access to at least oneterminal of the one or more circuit breakers of the electrical panel;using the tool to unclamp a wire from the at least one terminal of oneof the one or more circuit breakers of the electrical panel; removingthe insulating guard from the electrical panel; and replacing the frontpanel of the electrical panel.